Background: Systolic and fourth-phase and fifth-phase diastolic blood pressure (SBP, DBP4, DBP5) have appeared to differ in their patterns of age-related change, and SBP and DBP5 differ in their respective associations with anthropometric variables. Project HeartBeat! investigated trajectories of change in SBP, DBP4, and SBP5 with age and their relationships with indices of adiposity, controlling for energy intake, physical activity, and sexual maturation.
Methods: Project HeartBeat! was a mixed longitudinal study in 678 black and white girls and boys aged 8, 11, or 14 years at first examination, followed at 4-month intervals for up to 4 years (1991-1995). A statistical model was estimated for the trajectory of change in each blood pressure measure from ages 8 to 18 years.
Results: For SBP, DBP4, and DBP5, the trajectories were sigmoid, parabolic, and linear in form, respectively. SBP and DBP4 differed significantly by gender; DBP4 and DBP5 were significantly related to race. Adjusted for age, gender, and race, all relationships of adiposity-related variables (percent body fat, abdominal circumference, skinfold thickness, and BMI and its fat and fat-free components) with SBP were positive and significant. Corresponding relationships for DBP4 were notably weaker but significant, and for DBP5, weak or not significant. After adjusting for diet, physical inactivity, and maturation, no DBP5 relationship with adiposity indices remained significant.
Conclusions: SBP, DBP4, and DBP5 are distinct in patterns of change with age, relationships to gender and race, and patterns of association with multiple anthropometric indices related to adiposity.